Conventionally, refrigeration apparatuses, such as an air conditioning apparatus with a refrigerant circuit in which refrigerant circulates to perform a vapor compression refrigeration cycle, use refrigerants of the CFC (chlorofluorocarbon) family or refrigerants of the HCFC (hydrochlorofluorocarbon) family. However, the use of these refrigerants of the CFC/HCFC families gives rise to environmental problems such as ozone layer destruction. It is desired that these existing refrigeration apparatuses are renewed to new ones that employ refrigerants of the HFC (hydrofluorocarbon) family or refrigerants of the HC (hydrocarbon) family.
Refrigerant pipes for establishing connections between a heat source unit and utilization units are practically buried into inner areas of a building, therefore impeding replacement of such buried refrigerant pipes with new ones. For the purpose of shortening work periods and cutting costs down, the introduction of new refrigeration apparatuses is made while utilizing existing refrigerant pipes as they are.
Apart from the above, contaminants (e.g., refrigeration oil used in conventional refrigeration apparatuses employing CFC- or HCFC-family refrigerants with a chlorine content) remain as residual materials in existing refrigerant pipes. Conventionally, naphthenic mineral oil is often used as a refrigeration oil. If naphthenic mineral oil remaining as a residual material in an existing pipe degrades, this may give rise to the problem of corrosion of for example an expansion valve by the presence of chlorine ions and acids in the degraded mineral oil.
Accordingly when introducing a new refrigeration apparatus, it is necessary to clean existing refrigerant pipes to remove residual contaminants in the existing refrigerant pipes, prior to performing a test run on the new refrigeration apparatus.
To this end, there is proposed a refrigeration apparatus equipped with a refrigerant circuit which enables execution of an operation of cleaning existing refrigerant pipes (see, for example, Patent Document 1, Japanese Patent Laid-open Publication No. JP 2001-41613). The refrigeration apparatus of Patent Document 1, Japanese Patent Laid-open Publication No. JP 2001-41613 is provided with a refrigerant circuit formed by connection of a heat source machine mainly made up of a compressor and a heat source side heat exchanger with an indoor unit having a utilization side heat exchanger through existing connection pipes. And, an oil recovery unit for separating contaminants (such as residual refrigeration oil) from the refrigerant and recovering them is provided in a suction side pipe of the compressor.
The refrigeration apparatus of Patent Document 1 is configured, such that after the fill-up of the refrigerant circuit with a refrigerant of the HFC family, the compressor is activated and the refrigeration apparatus operates in cooling mode or in heating mode; existing connection pipes are cleaned by the refrigerant circulating in the refrigerant circuit; and contaminants (such as residual refrigeration oil) are recovered in the oil recovery unit.